The field of the invention relates to securing, strengthening and enhancing geo-positioning by satellite, in particular in the context of the use of geo-positioning equipment for the navigation of moving carriers.
It is applicable in many fields, for example aeronautics, maritime transport, road guidance, vehicle and robot guidance.
One favored field of application is that of the precision approach in aeronautics, based on the use of GNSS (Global Navigation Satellite System) navigation systems. For example, the American GPS (Global Positioning System) and the European GALILEO system are known.
A GNSS receiver is a device able to receive radio signals emitted by a plurality of satellites and to provide, after calculation, time-synchronization and position-reference information of the carrier in a geographical reference.
Each GNSS receiver extracts received time and carrier phase information sent in radio signals transmitted by various satellites, and calculates, for each satellite in view and from that received information, a positioning measurement, which is an estimate of the distance between the geo-positioning device itself and the satellite in view, which is also called pseudo-range. The pseudo-range is different from the actual distance between the satellite in question and the geolocation device due to errors in estimating the propagation delay, for example due to atmospheric conditions in the troposphere, in the ionosphere, and the synchronization error in the internal clock geo-positioning receiver. It is, however, possible to eliminate common errors (including the time bias of the receiver) by using the information sent by a plurality of separate satellites.
In many navigation applications, the precision, availability and integrity of the calculation of the position and the time bias are particularly important for the safety of the carrier.
There are several causes that may affect the integrity of the calculated geo-positioning position, for example any breakdowns or malfunctions of the satellites, the receiving chain of the geo-positioning device, various disruptions and interferences and/or deliberate and ill-intentioned jamming.
Known methods to increase geo-positioning make it possible to improve precision and provide solutions with greater integrity and robustness, for example the RAIM (receiver autonomous integrity monitoring), SBAS (satellite-based augmentation system), GBAS (ground-based augmentation system) systems.
However, these methods have limitations.
For an onboard system, improving the processing precision and robustness may involve high algorithmic complexity and require substantial processing resources.
Furthermore, the design of certified onboard systems is constrained by the regulations in force associated with the standardized processing architectures.
There is thus a need to validate and improve the geo-positioning precision provided by onboard radio navigation devices, while respecting the aforementioned constraints.